TOI-1338 c

This article is about the outer circumbinary planet of TOI-1338. For the inner planet discovered by Wolf Cukier, see TOI-1338 b.

TOI-1338 c
Discovery
Discovered byMatthew Standing et al. (BEBOP)
Radial velocity
Designations
BEBOP-1 c[a]
Orbital characteristics[1]
Epoch BJD 2458300.0
(30 June 2018 12:00 UT)[b]
0.794±0.016 AU[4]
Eccentricity0.037+0.032
−0.026[3]
215.79±0.46 d[3]
Inclination
  • 97.00°+6.70°
    −6.80°     (wrt sky)[3]
  • 9.1°+4.8°
    −6.0°     (wrt binary orbit)[3]
344.64°+25.87°
−31.25°[3]
Semi-amplitude5.6±1.0 m/s[4]
StarTOI-1338
Physical characteristics[3][1]
Mass75.4+4.0
−3.6 M🜨 (0.237+0.013
−0.011 MJ)[3]

TOI-1338 c (also known as BEBOP-1 c)[a] is a gas giant exoplanet orbiting the binary star system TOI-1338. The planet and its two stars are located in the constellation Pictor, about 1,300 light-years (400 parsecs) from Earth. It is the outermost known planet of the TOI-1338 planetary system, orbiting the stars' center of mass every 216 days at an average distance of 0.79 astronomical units (AU; 119 million km or 74 million mi). The discovery of the TOI-1338 c was announced in 2023, after it was detected in radial velocity measurements of its parent stars by the Binaries Escorted By Orbiting Planets (BEBOP) project during 2009–2022. The planet is estimated to be 75.4+4.0
−3.6 times more massive than Earth, although it has an unknown radius.[1]

Discovery

TOI-1338 c was discovered in spectroscopic observations of the binary star system TOI-1338, taken by the La Silla and Paranal observatories in Chile for the Binaries Escorted By Orbiting Planets (BEBOP) project during 2009 to 2022.[5][4]: 705  The BEBOP project was an astronomical survey intended to detect circumbinary exoplanets orbiting eclipsing binary stars using the radial velocity method,[4]: 705  which involves detecting the exoplanet's gravitational influence on its parent stars via Doppler spectroscopy.[6][7] The exoplanet's gravitational pull causes the parent stars to wobble with respect to Earth's line of sight, resulting in the stars appearing redshifted or blueshifted as they move away and toward Earth, respectively.[8][9]

The first sign of TOI-1338 c was reported in 2021 by a team led by Matthew Standing, who noticed a periodic 200-day radial velocity variation in the TOI-1338 star system.[5] The detection of this planet was confirmed after further observations took place in 2021 to 2022.[4]: 706  The discovery of TOI-1338 c was announced by Standing's team and published in the journal Nature Astronomy on 12 June 2023.[6][4] TOI-1338 c was the first circumbinary exoplanet discovered using the radial velocity method, and the TOI-1338 system was the second binary star discovered to host multiple circumbinary planets.[8]

Name

The planet's name follows the exoplanet naming convention of taking the parent star's name and adding a lowercase letter after it.[10] As it is the second exoplanet discovered orbiting the TOI-1338 star system, it is named TOI-1338 c.[10] The initialism "TOI" stands for "TESS Object of Interest", which is systematically given to the star system when TESS confirms a planet transiting it.[10] The TOI-1338 system is also known as BEBOP-1 because it was observed by the BEBOP project, so TOI-1338 c borrows the name BEBOP-1 c.[4][a] Since TOI-1338 c was discovered by the BEBOP project and was not observed by the Transiting Exoplanet Survey Satellite (TESS), Matthew Standing's team prefer the name BEBOP-1 c for the planet.[4]

Parent stars and location

Main article: TOI-1338

The parent stars of TOI-1338 b are a binary system consisting of a large, yellow-white F-type main-sequence star, and a smaller, red dwarf (M-type) star.[13][14] The larger star of the binary system, named A or the primary star, is hotter (temperature 6030 K), brighter (luminosity 2.1 L☉), and larger (radius 1.32 R☉, mass 1.13 M☉) than the Sun.[14][13]: 4581  The smaller star of the binary system, named B or the secondary star, is cooler (temperature 3300 K), dimmer (luminosity 0.009 L☉), and smaller (radius 0.31 R☉, mass 0.31 M☉) than the Sun.[14][13]: 4581  The two stars, collectively known as TOI-1338 (or BEBOP-1 or EBLM J0608-59), orbit each other every 14.6 days and are mutually separated by an average distance of about 0.13 astronomical units (20 million km or 12 million mi).[4]: 704 

The TOI-1338 system is known to host two circumbinary planets, which are named TOI-1338 b and TOI-1338 c.[1] Together, TOI-1338 and its planetary system are located in the southern constellation of Pictor, at a distance of about 1,300 light-years (400 parsecs) from Earth.[14] Viewed from Earth, TOI-1338 appears at an apparent magnitude of 11.7, which is too faint to be seen with the naked eye or a small telescope.[14]

Planetary properties

Orbit

TOI-1338 c is a circumbinary planet, meaning it orbits around two stars. For this reason, it is popularly compared to the fictional circumbinary planet Tatooine from Star Wars.[6][7][9] TOI-1338 c is the outermost known planet of the TOI-1338 system, orbiting 0.79 astronomical units (AU; 119 million km or 74 million mi) from the stars' center of mass with an orbital period of about 216 days.[3][1] It follows a nearly circular orbit that is somewhat coplanar to its parent stars.[4]: 704 [3]: 10  Specifically, it has an estimated orbital eccentricity of 0.037+0.032
−0.026 and a low inclination of 9.1°+4.8°
−6.0° with respect to the plane of its parent stars' binary orbit.[3]: 5, 11  Unlike its inner neighbor TOI-1338 b, the orbital inclination of TOI-1338 c is large enough that it does not transit its parent stars.[4]

Due to the orbital motion of the two stars, TOI-1338 c experiences periodic perturbations that cause its orbit to precess.[4]: 704  A 2023 study by Standing et al. estimated that TOI-1338 c's orbit exhibits nodal precession with a period of roughly 119 years.[4]: 704  As it precesses, TOI-1338 c's orbit may eventually align with Earth's line of sight, allowing the planet to begin transiting its parent stars.[4]: 704  However, it is uncertain when TOI-1338 c will begin transiting.[4]: 704 

Physical properties

Radial velocity measurements as of 2024 indicate TOI-1338 c has a mass 75.4+4.0
−3.6 times that of Earth's,[1] or about 79%±4% of Saturn's mass.[c] Based on its mass, TOI-1338 c is presumed to be a gas giant planet.[7][8][12] However, the planet's radius is unknown, because it has not been observed to transit its parent stars.[6][11]

Origin

Studies as of 2024 estimate that the TOI-1338 system is 6.0±0.3 billion years old, which is older than the Solar System.[13]: 4581  The coplanar orbits of planets and stars in the TOI-1338 system suggests that it formed from a single, flat protoplanetary disk.[3]: 11  Simulations by Gavin Coleman and collaborators in 2023 showed that circumbinary systems resembling TOI-1338 can form within 10 million years if the protoplanetary disk had low levels of turbulence (or viscosity) and ultraviolet irradiation.[12]: 425  These conditions limit the loss of protoplanetary material over time, which would allow the circumbinary planets to have more time and material to grow into gas giants.[12]: 419  According to simulations, the planets of the TOI-1338 system likely originally formed farther away from their parent stars, but migrated inward to their present-day locations.[12]

See also

Notes

  1. ^ a b c In the NASA Exoplanet Archive and the 2023 discovery paper by Matthew Standing et al., the names "TOI-1338 b" and "BEBOP-1 c" are written with a space between their prefixes and lowercase letter "c". While some news articles[6][7][11] and scientific papers[12] write the name as "BEBOP-1c" without the space, this Wikipedia article follows the format used by the NASA Exoplanet Archive.
  2. ^ The reference epoch of BJD 2458300.0 corresponds to the Universal Time (UT) date of 30 June 2018 12:00 UT,[2] which is approximately 90 days before the first observed transit by TOI-1338 b in TESS Sector 3.[3]: 4 
  3. ^ Saturn has a mass of 5.683×1026 kg, or 95.16 Earth masses.[15]

References

  1. ^ a b c d e f "TOI-1338 Overview". NASA Exoplanet Archive. Caltech IPAC. Retrieved 11 May 2026.
  2. ^ "JD Date/Time Converter". JPL Solar System Dynamics. NASA. Retrieved 10 May 2026.
  3. ^ a b c d e f g h i j k l Wang, Mu-Tian; Liu, Hui-Gen (25 June 2024). "Photo-dynamical Analysis of Circumbinary Multi-planet System TOI-1338: A Fully Coplanar Configuration with a Puffy Planet". The Astronomical Journal. 168 (1): 31. arXiv:2404.18415. Bibcode:2024AJ....168...31W. doi:10.3847/1538-3881/ad4a60. ISSN 1538-3881.
  4. ^ a b c d e f g h i j k l m n o Standing, Matthew R.; Sairam, Lalitha; Martin, David V.; Triaud, Amaury H. M. J.; Correia, Alexandre C. M.; Coleman, Gavin A. L.; Baycroft, Thomas A.; Kunovac, Vedad; Boisse, Isabelle; Cameron, Andrew Collier; Dransfield, Georgina; Faria, João P.; Gillon, Michaël; Hara, Nathan C.; Hellier, Coel (12 June 2023). "Radial-velocity discovery of a second planet in the TOI-1338/BEBOP-1 circumbinary system". Nature Astronomy. 7 (6): 702–714. doi:10.1038/s41550-023-01948-4. ISSN 2397-3366.
  5. ^ a b Standing, Matthew R.; Triaud, Amaury H. M. J. (July 2021). The First TESS Circumbinary Planet TOI-1338b / EBLM J0608-59b: A Possible Second Planet (PDF). Posters from the TESS Science Conference II (TSC2). virtual. Bibcode:2021tsc2.confE..95S. doi:10.5281/zenodo.5128770. Archived (PDF) from the original on 27 June 2022. Retrieved 9 May 2026.
  6. ^ a b c d e "A new Tatooine-like multi-planetary system identified". University of Birmingham. 12 June 2023. Archived from the original on 14 July 2023. Retrieved 11 May 2026.
  7. ^ a b c d Choi, Charles Q. (12 June 2023). "New Tatooine-like exoplanet discovered orbiting twin suns. Meet BEBOP-1c". Space.com. Retrieved 11 May 2026.
  8. ^ a b c Ram, Anand (12 June 2023). "New exoplanet discovery sparks hope of hidden 'Tatooines'". CBC News. Retrieved 11 May 2026.
  9. ^ a b Chandran, Anita (26 February 2026). "How astronomers found a real Star Wars-style 'Tatooine' planet with two suns". BBC Sky at Night. BBC. Retrieved 11 May 2026.
  10. ^ a b c Guerrero, Natalia M.; Seager, S.; Huang, Chelsea X.; Vanderburg, Andrew; Soto, Aylin Garcia; Mireles, Ismael; et al. (June 2021). "The TESS Objects of Interest Catalog from the TESS Prime Mission". The Astrophysical Journal Supplement Series. 254 (2): 39. arXiv:2103.12538. Bibcode:2021ApJS..254...39G. doi:10.3847/1538-4365/abefe1.
  11. ^ a b Anderson, Paul Scott (16 June 2023). "Second 'Tatooine' multiplanetary system discovered". Space.com. Retrieved 11 May 2026.
  12. ^ a b c d e Coleman, Gavin A. L.; Nelson, Richard P.; Triaud, Amaury H. M. J.; Standing, Matthew R. (January 2024). "Constraining the formation history of the TOI-1338/BEBOP-1 circumbinary planetary system". Monthly Notices of the Royal Astronomical Society. 527 (1): 414–427. arXiv:2310.11898. Bibcode:2024MNRAS.527..414C. doi:10.1093/mnras/stad3216.
  13. ^ a b c d Maxted, P. F. L.; Miller, N. J.; Sebastian, D.; Triaud, A. H. M. J.; Martin, D. V.; Duck, A.; et al. (July 2024). "Fundamental effective temperature measurements for eclipsing binary stars – V. The circumbinary planet system EBLM J0608−59". Monthly Notices of the Royal Astronomical Society. 531 (4): 4577–4583. arXiv:2406.04204. Bibcode:2024MNRAS.531.4577M. doi:10.1093/mnras/stae1434.
  14. ^ a b c d e "Star TOI 1338". stellarcatalog.com. Retrieved 11 May 2026.
  15. ^ "Planetary Physical Parameters". Solar System Dynamics. NASA Jet Propulsion Laboratory. 12 December 2019. Retrieved 11 May 2026.
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